Typical powder coatings include a flow modifier or flow control agent to control cratering and reduce orange-peel characteristics. Flow modifiers help control interfacial tension and surface tension of the powder coating during baking operations. Common flow modifiers include low glass transition temperature acrylics such as polylauryl acrylate, polybutyl acrylate, poly(2-ethylhexyl)acrylate, poly(ethylacrylate-2-ethylhexylacrylate), polylauryl methacrylate and the like. Fluorinated polymers, such as the esters of polyethylene glycol or polypropylene glycol, and fluorinated fatty acids are also used as flow modifiers.
Powder coatings are widely used in a variety of industrial applications. Some of these applications require recoatability, i.e., good recoat adhesion between the cured powder coating and a subsequent coating layer, so that minor imperfections or minor damages that may occur during shipment and transfer of industrial parts can be corrected. Unfortunately, powder coatings containing the common flow modifiers have been found to have poor recoat adhesion.